# Power rating of this snubber resistor

#### Xavier Pacheco Paulino

Joined Oct 21, 2015
728
Hi,

I attach an schematic that represents an application of the MOC3061. It's been extracted from the datasheet. My question is: How can I determine the power rating for that 39 ohms resistor?

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#### Bordodynov

Joined May 20, 2015
2,736
The average power (27uW), voltage and currents are very small (at this value of the capacitor). But there is a voltage limitation (377V) and an impulse current (~ 10A)

#### ericgibbs

Joined Jan 29, 2010
11,608
hi Xavier,
Look thru this PDF.
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#### casteels

Joined Mar 22, 2012
9
That will be low: the impedance of a 0.01u capacitor at 50Hertz is 1/2*pi*50*0.01e-6 = 318K.
Maximum current is less then 1mA at 220V. Power is then i^2*39

#### Dodgydave

Joined Jun 22, 2012
9,855
Hi,

I attach an schematic that represents an application of the MOC3061. It's been extracted from the datasheet. My question is: How can I determine the power rating for that 39 ohms resistor?
The Xc of the capacitor will be 318K ohms @ 50Hz, so max current will be less than 1mA, use a 1/8 or 1/4 W ..

#### Bordodynov

Joined May 20, 2015
2,736
Look at the pulsed currents and voltages: